This invention relates to an applicator for semisolid substances such as gels, solutions and emulsions onto a body surface. More particularly this invention relates to an applicator of semisolid substances without the need for any pressure compensating mechanisms.
There is a continual search for better ways to apply a lotion, gel, solution or emulsion to the skin surface. The substance can be a deodorant, antiperspirant, suntan lotion, poison ivy preparation or some other substance which is to be delivered to the skin. Since the substance is only a semisolid, it cannot function as the applicator surface. Solid stick deodorants and antiperspirants function as the applicator surface. No separate applicator surface is needed. However, with semisolid substances a separate applicator surface is needed.
There are several different types of applicator surfaces that have been and are being used. In U.S. Pat. No. 4,801,052 and U.S. Pat. No. 5,372,285 there is disclosed a rigid applicator section that has a plurality of apertures. The semisolid material flows directly through the holes in the rigid surface and is applied to a body surface. These apertures can be of varying shapes and sizes, and in varying numbers. This is exemplified in the commercial Mennen Speed Stick gel products and the Right Guard gel products.
Another applicator for semisolid products is to use a Porex applicator surface. Porex is a sintered plastic material that has random, nonlinear, branched pores of varying cross-sectional diameters. Also, the pores are much smaller in cross-section than the apertures of U.S. Pat. No. 4,801,052 or U.S. Pat. No. 5,372,285. In these porous applicators the individual pores will be in a varying diameter of about 150 to 400 microns. This is much smaller than the apertures of the above two U.S. Patents. However, these porous materials pose a post-extrusion problem. Post-extrusion is the continued flow of the semisolid substance after the cessation of the force to push the semisolid substance through the applicator surface. This is a problem since it flows after the application of the product, is wasted product, and is considered as being messy.
This problem has been addressed by incorporating a pressure relief mechanism into the dispenser. Such pressure relief mechanisms are shown in U.S. Pat. No. 5,540,361 and U.S. Pat. No. 5,547,302. These pressure relief mechanisms allow the elevator to recede away from the applicator surface in a dispensing stroke. This relieves most of the pressure in the applicator that would cause post-extrusion through the applicator surface.
U.S. Pat. No. 5,547,302 also discloses the use of a mesh as the applicator surface. This mesh is comparatively thin and flexible with a plurality of discrete openings extending through the mesh. This can be from the structure of a screen to a rigid structure. In the Example the mesh thickness is 0.022 inches. However, regardless of its structure or thickness, the mesh structure has a post-extrusion problem. The dispenser with this mesh applicator surface requires the use of a pressure relief mechanism in conjunction with the elevator of the dispenser. As with the Porex microporous applicator surfaces, there is needed a mechanism to prevent any substantial post-extrusion. However, all of these pressure relief mechanisms add to the complexity and cost of the dispenser.
The present invention solves this problem. Semisolid substances can be delivered through an application surface having pore-like openings without the problem of post-extrusion. This is accomplished by the use of one or more plies of a mesh fabric. The fabric has substantially linear openings through the fabric. Whether there will be one ply or a plurality of plies will depend on many factors including the structure of the fabric. This will depend to a large degree on the fiber denier and the weave of the fabric if it is a woven fabric, the size of the apertures for an extruded nonwoven film fabric, and the porosity of the fabric if it is a nonwoven with random arrayed fibers. One objective is to have fabric of a material that is heat bondable to a peripheral frame edge and through which a product of a rheology of about 10,000 centipoises to about 1,000,000 centipoises can flow without any substantial post extrusion. It is preferred in the present dispenser to use a single ply fabric of a denier and weave that maintains its structural integrity in use to apply a substance to the skin, with or without the use of an underlying support structure. That is, there is no folding or undue distortion of the fabric surface during the application of the semi-solid substance. Some flexing is desired in order to follow the contours of the skin. However, this flexing should not result in any permanent distortion of the fabric surface.
As an option a plurality of fabric plies can be used. In such an instance there will be from about 2 to 10 plies, and preferably 2 to 5 plies. By randomly overlaying plies of the fabric, the openings are partially juxtaposed from ply layer to ply layer. This provides for a modified circuitous path of the substance through the mesh fabric. An additional force is needed to flow the semisolid substance through the multi-ply fabric structure versus a single ply structure, but not a force that would result in any significant post-extrusion or leakage of the semisolid substance. The applicator fabric will be matched to the viscosity of the formulation. The flow through the fabric plies is substantially simultaneous with the application of pressure to the semisolid product with there being no pressure to be dissipated after the use of the dispenser.
In addition to the advantages of no substantial post-extrusion the use of a mesh fabric provides for an improved product shearing of the semi-solid substance and more uniform application to the contours of the body surface. Improved shearing allows for the application of a thinner continuous layer of the semisolid substances onto the skin.
The present invention is directed to a dispenser with an applicator surface that does not require a pressure relief mechanism to prevent the post-extrusion of the substance being dispensed. The applicator surface is comprised of one or more layers of a mesh fabric. The structure of the fabric will depend on whether the fabric is woven or nonwoven. A nonwoven fabric includes extruded films having apertures and fabrics of a layer of random arrayed fibers. When a plurality of plies are used, the plies can be in a designed array or in a random array. The result in the use of a plurality of plies is a plurality of offset passageways. This arrangement of offset passageways provides for some back pressure in the dispensing of the semisolid substance, but not a pressure that would result in any significant post-extrusion flow. The flow ceases fairly quickly upon the cessation of the application pressure since the application pressure is quickly relieved by the direct flow of the semisolid substance. The fabric can be used with or without an underlying support. Whether in the form of a single or multiple ply, there is provided a surface that will conform to the small undulations in the body surface to which the semisolid is being applied.
The fabric can be a woven or a nonwoven fabric. If woven it can have a plain twill or satin weave. The weave also can be a tight or a loose weave. Further, the fibers that comprise the fabric can be in a range of deniers. If nonwoven, the fabric can be an extruded film with microporous apertures or can be produced by one or more random layers of fibers that are bonded together. The only requirements are that the fabrics be thermoplastic and be heat bondable to a thermoplastic frame, and that in use as an applicator surface for a viscous semisolid substance that there be no significant post-extrusion of the viscous semisolid after application to a skin surface. If woven, the mesh apertures will be more uniform in structure. Whether woven or nonwoven, the applicator surface will be comprised of about 1 ply to about 10 plies of fabric, preferably about 1 ply to about 5 plies and most preferably about 1 to 3 plies. The mesh openings nominal (average) size will be in the range of about 50 microns to about 1,000 microns, and preferably about 80 microns to about 400 microns. In a multilayer structure the mesh openings in one layer usually will not align with the mesh openings of another layer. However, the mesh openings can be arranged to be aligned from layer to layer. Further, the mesh openings can vary in size from layer to layer. The mesh openings will have a nominal surface area of about 2.5xc3x9710xe2x88x923 mm2 to about 1 mm2 and preferably about 6.4xc3x9710xe2x88x923 mm2 to about 0.16 mm2. This variability in alignment and in mesh size can accommodate compositions of different rheologies. The rheology of the composition to be delivered and the mesh opening size or sizes are coordinated in order to deliver a viscous product without the need for a pressure relief mechanism in the dispenser.
The mesh fabric will have a thickness of about 0.032 centimeters to about 0.30 centimeters and preferably 0.041 centimeters to about 0.15 centimeters. The mesh fabric provides a variation of skin feel in the application of substances. By varying the fabric material and the size of the aperture openings, the skin feel can be changed from soft and smooth to a noticeable skin rubbing. There can be a low to high degree of skin friction. The skin feel also can be changed by calendaring the sheet material to change surface characteristics such as the coefficient of friction.
The applicator support structure can be comprised of a plurality of support ribs across the major axis or minor axis of the dispenser. Such ribs preferably would have a radius of curvature of about 10 centimeters to about 20 centimeters along the major axis and about 2.54 to 7.62 centimeters about the minor axis. These ribs support the fabric in a compound curve structure. They allow some flex in the fabric but do not allow for any permanent distortion of the fabric. Optionally the support structure can be a rigid apertured section. In this embodiment there will be no flex to the fabric surface.
In one mode of use a knob in a lower part of the dispenser will be rotated to move an elevator in the dispenser upward. This will provide for a flow of some of the viscous semisolid substance supported on the elevator through the fabric applicator surface. There is no discernible post-extrusion flow of the semisolid substance after the dispensing of the desired amount of the semisolid substance and the application of this substance to a body surface. The internal pressure in the dispenser is rapidly equilibrated with the exterior pressure upon the movement of the elevator to dispense the semisolid substance. There is no resulting back pressure after the use of the dispenser to cause any significant post-extrusion of the semisolid substance.